Spanish police say they have confiscated 310 kilos (683 pounds) of young eels that were about to be smuggled out of the country and shipped to Asia.

The Civil Guard said on Saturday that officers and customs agents at the Madrid airport impeded two shipments of eels during the past week.

The agents discovered 250 kilos (551 pounds) of young eels hidden in packages that were labeled as carrying barnacles destined for Vietnam. They later found four bags checked for a flight to Hong Kong holding another 60 kilos (132 pounds.)

The European Union prohibits the import or export of the European eel, which is considered a species at risk of becoming endangered without trade controls.

The Civil Guard says that the confiscated eels were released in rivers.